By using various methods, an inkjet printing apparatus forms a discharged droplet of ink, and makes this discharged droplet stick to a printing medium such as a printing paper sheet to print. More specifically, the inkjet printing apparatus (to be referred to as a printing apparatus hereinafter) which uses thermal energy for forming the discharged droplet has good features in which a plurality of orifices are easily arranged at high density, a high-resolution and high-quality image can be obtained at high speed in this high-density arrangement, and a color image can also be obtained easily.
In actual printing processing, such printing apparatus discharges the ink on the printing medium in accordance with a supplied printing signal to print. Since the printing apparatus achieves low running cost and operates quietly, this printing apparatus is widely used.
Also, in a color printing apparatus, a printhead which discharges a plurality of color inks discharges the color ink droplets on the printing medium in an overlaying manner so as to form a color image. Generally, inks of three primary colors, i.e., yellow (Y), cyan (C), and magenta (M) are respectively stored in three ink cartridges, and inks of four colors obtained by adding black (K) to the three primary colors are respectively stored in four ink cartridges. The inks are supplied from these ink cartridges to the three or four printheads corresponding to these ink cartridges to print.
Recently, a head cartridge formed by integrating the printheads for discharging the four color inks and the ink cartridges is available. Also, in order to obtain a more high-quality image, the printing apparatus which prints by using seven color inks obtained by adding pale yellow (PY), pale cyan (PC), and pale magenta (PM) to the four colors, i.e., Y, M, C, and K colors is available.
Note that the printing apparatus includes a serial-scan-type printing apparatus and a line-head-type printing apparatus. In the serial-scan-type printing apparatus, a carriage to which the printheads are mounted is scanned in a certain direction (this direction is called a main scanning direction), the printing medium is conveyed in a direction perpendicular to the main scanning direction (this direction is called a sub-scanning direction) for each main scan, and an image is serially printed on the printing medium positioned on a platen. In the line-head-type printing apparatus, the full line printhead having a great number of printing elements is fixed in a direction perpendicular to the conveyance direction of the printing medium, and the image is printed on the printing medium conveyed on the platen.
The latter (line-head-type) printing apparatus includes a convey mechanism capable of continuously conveying the printing medium, and conveys the printing medium positioned under the fixed full line printhead to print, thereby printing at very high speed. However, since the line-head-type printing apparatus uses the full line printhead, the apparatus becomes large. Further, since the full line printhead is expensive, the apparatus becomes expensive.
To the contrary, the former (serial-scan-type) printing apparatus includes a convey mechanism capable of intermittently conveying the printing medium in accordance with the print width of the printhead, and prints by repeating the conveying operation of the convey mechanism and the printing operation of the printhead. Therefore, the serial-scan-type printing apparatus can be small and provided at low cost even though the printing speed is low (see Japanese Patent Publication Laid-Open No. 2002-103709).
Conventionally, the line-head-type label printer which can print at high speed is generally used. However, since the recent serial-scan-type label printer can also attain high printing speed by largely increasing the number of nozzles of the printhead, such a printing apparatus is used as a label printer by utilizing the advantage that the apparatus is small and provided at low cost.
FIGS. 13A to 13C are views showing a scenario in which the serial-scan-type label printer continuously prints a plurality of labels. FIGS. 13A to 13C are views of a label layout sheet viewed from a direction perpendicular to the main scanning direction of a printhead 300, and to a conveyance direction (sub-scanning direction) of the layout sheet on which labels 303 are stuck. In such continuous printing operations, after printing the first label, the label layout sheet is moved to a printing start position of the next label, then the printing operation for the next label is started.
FIG. 13A shows a state where a label layout sheet 302 is fed. In this state, the label layout sheet 302 on which the plurality of labels are stuck is fed and conveyed, and the leading end of the first label 303 reaches the position of a photo-transmission type of a TOF sensor 301. When the TOF sensor 301 senses the leading end of the label 303, the label layout sheet is temporarily stopped at this position. Then, printing information received from a host (not shown) is printed on the label 303 by repeating the conveyance of the label layout sheet and the scan of the carriage to which the printhead 300 is mounted.
FIG. 13B shows a state where the trailing end portion of the first label 303 has been printed, the printing of the first label 303 has been completed, and the leading end of the next label 304 is conveyed over the TOF sensor 301.
FIG. 13C shows a state before printing the printing information on the next label 304. The leading end of the label 304 is set at the printing position by conveying the label layout sheet 302 in a reverse direction from the state shown in FIG. 13B.
As described above, in a case where a plurality of labels are continuously printed, one of the following methods is generally used. (1) After printing on one label, the label paper sheet is moved to the printing start position of the next label to print on the next label. (2) A plurality of labels to be continuously printed are defined as one page, and the printing data of one page is transferred from a host (not shown) to print. (3) Blank data of a width corresponding to the interval between the labels is added between the plurality of labels to be continuously printed, the plurality of labels to be continuously printed are defined as one page, and the data is transferred from a host (not shown) to print.
However, in the prior art, in a case where the method (1) is employed, for example, when continuously printing on a plurality of labels arranged in a printable area, of a printing medium, by a single scan of the printhead as shown in FIG. 13B, the label layout sheet needs to be moved to the printing start position of the next label after printing on one label. Hence, the throughput of the printing operation may be badly reduced.
In a case where the method (2) is employed, a printing medium such as a label layout sheet on which a plurality of labels are stuck with adequate intervals cannot be used for printing. In a case where the method (3) is employed, the printing position may be shifted to the label position if the label interval does not match the convey control of the set label layout sheet.